Vertebrates Aids Human Anatomy...adultlowervertebrates,whileheisstudying,microscopically,bysection orreconstruction,the same conditions as temporaryembryonal stages in the development

Comparative Anatomy and Embryology of

Vertebrates as Aids in the Teaching

of Human Anatomy in the

Medical Course .

BY

GEORGE S. HUNTINGTON, M.D.,

NEW YORK.

FROM

THE AMERICAN JOURNAL OF THE MEDICAL SCIENCES,

December, 1898.

THE

COMPARATIVE ANATOMY AND EMBRYOLOGY

OF

VERTEBRATES AS AIDS IN THE TEACHING OF HUMAN

ANATOMY IN THE MEDICAL COURSE.

1

By GEORGE 8. HUNTINGTON, M.D.,NEW YORK.

I feel some diffidence in addressing the Association on the subject

of my title, for I have before me, through the courtesy of Prof. Wilder,

papers and pamphlets dealing more or less definitely with the general

question involved, written by Hyrtl, Waldeyer, and Turner amongforeign anatomists, and by Wilder, Allen, Baker, and Minot amongour own countrymen, and the list proves that the matter has received

due thought and consideration at the hands of the ablest investigators

and teachers of our science. If, notwithstanding, I bespeak some of

your time and attention, it is not because I wish to repeat what has

already been said by the eminent men quoted far better than I could

hope to express it, but because the question is a many-sided one, and

because I desire to emphasize certain aspects of the same in their prac-

tical bearing on anatomical instruction at our medical schools.

I may state at the outset that I do not propose to discuss the question

whether comparative anatomy should be included as a separate depart-

ment of study in the medical course ;

2but, as my title indicates, I wish

1 Read before the Association of American Anatomists, Tenth Session, at Cornell University,

December 30, 1897.

2 Wilder, Burt G. Should Comparative Anatomy he Included in a Medical Course? NewYork Medical Journal, October, 1877.

Wilder, Burt G. The Anatomical Uses of the Cat. New York Medical Journal, Octl 1879.

Turner, William. Address at the opening of the Anatohiica.1 Department in the new medi-

2 HUNTINGTON: AIDS IN TEACHING ANATOMY.

to bring before you the employment of both comparative anatomy and

embryology of vertebrates as aids in instructing medical students in

human anatomy. Nor do I desire to speak of the advantages of pre-

liminary work in comparative anatomy and embryology to students

intending to enter the medical curriculum, beyond adding my testimony

to the effect that the value of such preliminary work cannot, in myexperience, be overestimated. I have occasion annually to compare the

work and progress of a large number of students from all parts of the

country and to note that almost without exception the men who early

demonstrate their ability are those who have received practical biological

training during their college course.

The questions which I wish to present for your consideration deal with

the situation which confronts us, I believe, at the majority of our large

centres of medical education, where students, differing necessarily widely

in mental attainments, quantity as well as quality of preliminary train-

ing, meet to enter the medical curriculum, and are almost at once intro-

duced to the study of human anatomy.

I may add that we have at Columbia during the past six years ear-

nestly and systematically employed in our instruction in human anatomy

the aids which the development and morphology of the lower verte-

brates offer, so that the method upon which I can report to you has, to

a limited extent, stood the practical test of experience.

The advances of the last decade in the biological sciences have changed

and modified, in important and vital details, the method and scope of

morphological instruction. Among the special departments in our large

universities the one charged with teaching the structure of the humanbody to medical undergraduates should perhaps be the first to avail

itself of these wider views and broadened fundamental lines. Humanmorphologists have long occupied a peculiar position in relation to their

subject of study. For over two centuries the most minute and pains-

taking care has been bestowed on the investigation of man’s structure,

both the gross anatomy and the histology of his tissues receiving exhaus-

tive attention. The results, embodied in almost countless volumes and

pamphlets, make man to-day morphologically the best-known vertebrate.

cal building of the University of Edinburgh, October 27, 1880. Reprinted from the Lancet,

November 6 and 13, 1880.

Minot, Charles Sedgwick. A Grave Defect in our Medical Education. March, 1882. Reprint.

Baker, Frank. The Rational Method of Teaching Anatomy. Read before the Biological

Society of Washington, D. C., November 30, 1883. New York Medical Record, April 19, 1884.

Waldeyer, Prof. Dr. Wie soil man Anatomie lehren und lernen ? Rede gehalten zur Feier

des Stiftungstages der Militar-arztlicnen Bildungsanstalten am 2. August, 1884. Berlin, 1884.

Baker, Frank. What is Anatomy? A lecture delivered October 5, 1887, at the opening of

the anatomical course at the Medical Department of the University of Georgetown, Washington,

D. C. New York Medical Journal, October 22, 1887.

Allen, Harrison. Addresses in Anatomy: I. Comparative Anatomy as a Part of the Medi-

cal Curriculum. II. On the Teaching of Anatomy to Advanced Medical Students. Philadel-

phia, 1891.

HUNTINGTON: AIDS IN TEACHING ANATOMY. 3

This accrued knowledge is at our disposal, and is receiving constant

additions, as from time to time one field after another of human anat-

omy is revised and studied with modern methods of investigation. I

believe that our duty as teachers of this knowledge requires us to take

cognizance, thoroughly and systematically, of the structural relationship

of man to the remaining vertebrates; to incorporate comparative anat-

omy and embryology more completely in our course of instruction to

medical students to a degree and in a manner which the following pages

will present briefly for your consideration.

In the first place I believe that we should not lose sight of what we

may term the liberal scientific education of our students, as opposed to

the acquisition of purely technical professional knowledge. Even a few

years ago many fundamental facts of comparative anatomy and evolu-

tion were the scientific property of a limited number of special investi-

gators. But with the general growth of education, especially within the

direct sphere of influence of our large universities, much of this knowl-

edge has become diffused among the laity. It is almost superfluous to

mention the wide educational effect of institutions like the American

Museum of Natural History, the Army Medical Museum, or the

National Collection.

In his relation to the community at large the physician is still par

excellence the man of science, and I believe that as a matter of general

scientific education he should possess a knowledge, founded on his uni-

versity course, which will enable him to give information and express

intelligent opinions on vertebrate morphology in general and in relation

to the structure of man.

But, aside from this general aspect, the study of comparative forms is

of the greatest possible practical benefit to the medical student. I

vividly recall my own student days, and I cannot but sympathize with

the feeling, more or less akin to despair, with which many students begin

to apply themselves to the minute details of structure taught in humananatomy. It seems to me that it is wise to compare our system of

instruction with that usually adopted in some other branches of scien-

tific and mechanical education. It would be universally acknowledged

a wrong course of procedure if a student of mechanical engineering

were taught the constructive details of a modern locomotive, or of the

quadruple expansion engines of an ocean steamer, before he bad been

offered the opportunity of examining and studying the simple piston,

cylinder, or boiler;

or if a course in electricity commenced with the

dynamo, before taking up the magnet. And yet I believe that in manyrespects we err in the same direction if we place before our students the

multitudinous details which the structure of a highly developed and

specialized vertebrate like man offers, without availing ourselves of the

advantages which the comparison with simpler and more evident forms


possesses both in respect to morphology and the physiological appli-

cation of structure to function.

I am aware that in the last years much progress has been made in the

direction indicated, especially in the teaching of human anatomy from

the developmental stand-point. My plea to-day is for the further elab-

oration of this method and for the systematic use of comparative anat-

omy in teaching the structure of the human body to medical students.

Even with the best intentions it is not always possible fully to utilize

the help which embryology offers in explaining the details of compli-

cated adult human structures. I believe firmly that lasting knowledge

is only attained by bringing the student into direct contact with the

object of his study. The very nature of embryological methods pre-

sents difficulties in this respect, for practical laboratory work in embry-

ology is a sine qua 7ion for successful instruction, and drawings or models,

schematic or otherwise, do not replace the actual object if we seek to

elucidate adult structures by developmental facts. Hence comparative

anatomy steps in to fill an important gap in our available methods,

enabling us to present in tangible shape the fundamental facts in the

development of the higher mammalian forms, our own included, by

properly selected preparations of lower types which preserve throughout

life morphological conditions that are temporary and evanescent embry-

onic stages in the higher forms. Where possible, I believe a course of

practical laboratory embryology should be offered to medical students,

and my ideal of such a course would be one which puts into each stu-

dent’s hand preparations designed to illustrate, as they do forcibly and

unequivocally, the main structural facts as permanent conditions in the

adult lower vertebrates, while he is studying, microscopically, by section

or reconstruction, the same conditions as temporary embryonal stages in

the development of the higher forms. We tell our students that the

mammalian pancreas develops as a double diverticulum of the duodenal

loop, and thus explain the connection of the pancreatic ducts with this

portion of the intestinal tract. I believe that this fact would impress

itself far more permanently if at the same time they were able to

examine a selected series of pancreatic structures and pyloric cseca,

beginning, for instance, with the double diverticulum of Lophius and

working through representative Teleost types to the pancreas of higher

forms. The very fact of the morphological variations and the probably

different physiological adaptations encountered in this portion of the

intestinal tract in lower vertebrates, together with the variations in the

arrangement of the pancreatic and biliary ducts in mammalia, render a

serial study of this kind all the more valuable. Again, I know of no

method which will teach the medical student in a short time more about

the structure of the penis than to demonstrate to him a series of rep-

tilian copulatory organs, where at a glance he can see the morphological


principles underlying the development of the mammalian corpus spongi-

osum and urethra, conditions which he will invariably recall when he

examines his first clinical case of hypospadias. I cannot burden you

with further examples;they suggest themselves by the score

;but I

believe you will agree with me if I add that one demonstration of the

simple carnivore or marsupial intestinal tract and peritoneum is worth

tons of colored chalk and acres of blackboard in elucidating the mys-

teries of the “ greater and lesser sac.”

So much, briefly, for the connection of comparative anatomy with the

practical laboratory course in embryology. If I may trespass further

on your time, I should like to point out what in our experience has

proved the proper place for the introduction of comparative anatomy

into the general course on adult human anatomy.

I may state again, that in constructing the anatomical course at

Columbia the guiding principle has been found in the conviction that

the student will gain his lasting and valuable knowledge only by direct

study of the cadaver. We have broken—1 hope for good and all—with

the didactic lecture in anatomy as commonly understood, and I maytake a moment to outline our procedure, because it directly involves the

question in hand. The first-year student attends no lectures in anatomy.

During this year the instruction consists of practical demonstrations to

small sections of the class, dealing with the anatomy of the extremities,

the osteology, myology, and angiology of the head and neck, including

the cervical plexus, and in direct connection with the demonstrations

abundant practical work in the dissecting-room. The first-year student

also attends a series of demonstrations forming what we term the “ Pre-

liminary Visceral Course,” designed to afford that general information

regarding the body cavities and contents which is required for the cor-

rect appreciation of the instruction offered by the Departments of Physi-

ology and Histology.

In the second year, the laboratory Avork continuing, the student

attends demonstrations to sections of the class in the anatomy of the

central nervous system, organs of special sense, and cranial nerves.

The entire second-year class attends three lectures a Aveek on the anat-

omy of the body cavities and viscera. The preparations illustrating

these lectures are, in the afternoons of the lecture days, demonstrated

again separately to sections of the class, enabling each man carefully lo

inspect and study the same. In this way the opportunity is given of

making the anatomical lecture Avhat, in my opinion, it should strive to

be—not an attempt to teach anatomy at long range to three hundred

men at once, but an occasion for presenting a general view of the broad

morphological principles Avhich underly the construction of organs,

apparatus, and systems. It is here that the significance and impor-

tance of the structural peculiarities of man can best be accentuated

6 HUNTINGTON : AIDS IN TEACHING ANATOMY.

and illustrated in all their bearings by comparison with the morphology

of the lower vertebrates. A series designed to teach the evolution of a

complicated human organ, through successive stages from the simple

and rudimentary form found in the lower vertebrates, or, conversely, the

phylogenetic history of a human vestigial organ serially illustrated,

attracts the student’s attention and interest from the outset. He is

offered actual facts and preparations, not dry statements or schematic

drawings, and the knowledge cannot fail to be more readily acquired and

more throughly assimilated. “ Seeing is believing,” in anatomy as else-

where. At times, in dealing with broad general themes and subdivisions

of the subject, as the genito-urinary tract, the digestive system, etc., I

find it desirable to present a bird’s-eye view of the structures under

discussion by bringing before the students series of representative forms

from all the vertebrate classes and orders before proceeding to details.

Here the projection of photographs of the actual preparations by means

of the lantern gives excellent satisfaction, although it does not, in myopinion, replace the personal examination of the object at close range.

I may conclude by outlining, in the case of a single organ, the scope

and extent of the comparative method as we have used it profitably in

practice. I have selected the lung, because a subsequent communica-

tion which I have to make to the Association on the mammalian epar-

terial bronchial system will enable me to present my illustration in a

somewhat more complete form.

We begin our study of the respiratory system with a brief considera-

tion of the physiological significance of the structures involved, as illus-

trated by the following scheme (Fig. 1).

Fig. i.

oI

- - -> R.M.E A

c

Scheme of respiratory apparatus.

R.M. Respiratory membrane. A. Afferent vessel. E. Efferent vessel. C. Respiratory capil-

lary net-work. O. Medium containing oxygen.

In addition to tegumentary respiration two general types of verte-

brate respiration are to be recognized, depending upon the character of

the oxygen-medium, whether water or air, and presenting corresponding

structural modifications:

1. Medium: Water; respiratory organ:

gills.

2. Medium : air;respiratory organ : lung.

We begin with respiration and the connected portion of the circula-

tory system in a representative fish, and select the selachian skate (Raja

HUNTINGTON: AIDS IN, TEACHING ANATOMY. 7

occellata) because it affords peculiar facilities for demonstration (Figs. 2

and 3).

The afferent arterial system proceeds from the truncus arteriosus of

the single-chambered ventricle, dividing into caudal and cephalic

branches, of which the former supplies three, the latter two branchial

arteries to the gills (Fig. 2). These vessels carry venous blood returned

Fig. 2.

Heart, afferent branchial arteries, and gill-arches of Raja occellata ; ventral view.

to the heart by the ducts of Cuvier emptying into the single auricle.

The blood, after traversing the gill capillaries and becoming arterial-

ized, is collected by a corresponding number of efferent branches which

pass caudad and mesad on the dorsal aspect of the oesophagus, uniting to

form the aorta which distributes the blood to the body, to be returned

by the systemic veins to the auricle of the heart (Fig. 3).

Dorsal view of gill-arches, efferent vessels, and aorta of Raja occellata.


The type here represented can be reduced to the following scheme

(Fig. 4).

If now we assume that one gill on each side (the fifth) is replaced by

a lung in the evolution of air-breathing vertebrates, and the correspond-

ing arterial arch (the fifth) divided by the aortic septum from the sys-

temic artery and converted into a pulmonary artery, the remaining four

gills being no longer required, the continuity of the four cephalic arte-

Fig. 3.

rial arches will be restored. We will then have, with the divided heart

and truncus arteriosus necessitated by the establishment of a pulmonary

respiration, the following arrangement, which will be recognized as the


fundamental type-plan in the development of the arterial system of all

lung-breathing vertebrates.1 (Fig. 5.)

That the above assumption is justified is shown by the arrangement

of the circulatory system in the perennibranchial amphibia; and the

lung-fishes, and the circulatory system of Necturus and Menopoma, as

well as that of Ceratodus, are here introduced as demonstrative objects.

(Schematically represented in Figs. 6, 7, and 8.)

Fig. 4.

Scheme of circulation of Raja occellata.

1. Afferent branchial artery. 2. Capillary net-work of gill. 3. Efferent branchial artery.

4. Aortic root. 5. Aorta.

The points which our consideration of the subject so far has developed

may be summed up as follows :

1. Unity of structural plan in all vertebrates.

2. Physiological equivalence of gill and lung.

1 The development of the heart and arterial system has been considered in the course priorto the taking up of the respiratory system.

10 HUNTINGTON : AIDS IN TEACHING ANATOMY.

3. Pulmonary respiration and the necessary concomitant changes in

circulation cause the transformation of the simple two-chambered (venous)

fish heart into the four-chambered (arterio-venous) heart of the higher

air-breathing vertebrates.

4. The arterial arches pass ventro-dorsad around the foregut, uniting

to form the aorta on the dorsal aspect of the canal.

Fig. 5.

1

1-5. Aortic arches. 6, 6. Aortic roots. 7. Aorta. 8, 8. Lungs. 9. Right (pulmonary) ven-

tricle. 10. Left (systemic) ventricle.

Hence in anomalous persistence of both right and left aortic arches

in man the trachea and oesophagus are included within a vascular loop.

(Demonstration of correlated human aortic variations.)

We next turn to the derivation of the lung which, as above assumed,

supplants the gill. Here again we begin with the type presented by

the fish.

The gill-clefts of the fish correspond to the visceral clefts formed

during the embryonic stages of the higher vertebrates.


Complete clefts are formed by protrusions from the wall of the fore-

gut, pouches extending laterally and finally perforating externally,

establishing a passage between the pharyngeal cavern and the surface.

The number and arrangement of the clefts in the fish vary. In the

embryos of the higher vertebrates there are usually four or five.

Caudad of the last gill-cleft in the fish an additional protrusion of

the wall of the gut forms the “ swim-” or “ air-bladder,” variable in

development and purely hydrostatic in function. Three types of the

swim-bladder are now exhibited :

1.

Selachian (Raja). Bladder absent, except possibly represented bya rudimentary diverticulum of the dorsal pharyngeal wall.

Fig. 6.

Scheme of circulation in the Perennibranchial Amphibia.

1. Afferent branchial artery. 2. Capillary net-work of gill. 3. Efferent branchial artery.

4. Aortic root. 5. Pulmonary artery. 6. Lung. 7. Aorta.

2. Ganoid (Acipenser). Bladder present, connected with the lumenof the oesophagus by a hollow stalk, the ductus pneumaticus.

3. Teleost ( Gadus). Bladder variable in its occurrence, more or less

reduced. The ductus pneumaticus persists in a few forms in a rudimen-

tary condition.

In most forms the bladder loses its original connection with the oesoph-

agus and becomes entirely closed. The contained “ air,” composed of

varying proportions of oxygen, nitrogen, and carbon dioxide, is derived


from the blood, which in the branchial circulation absorbs air from the

water and again gives it off from a “rete mirabile” placed on the

internal surface of the swim-bladder.

An examination of the cod’s bladder demonstrates the following

points :

1.

A closed sac, no communication with the oesophagus existing.

Fig. 7.

Scheme of circulation in the Dipnoi.

1. Cephalic aortal arch. 2, 3, 4. Capillary net-work of gills connected with 2d, 3d, and 4th

arches. 5. Pulmonary arch. 5'. Ductus arteriosus. 5". Pulmonary artery. 6. Aortic root.

7. Aorta. 8. Swim-bladder or lung.

2. Lateral prolongations and blunt processes, resembling the mar-

ginal diverticula of some reptilian lungs.

3. Cephalic narrow tubular prolongations, possibly associated with

the acoustic apparatus.

4. On the internal surface of the ventral wall the vascular “ rete

mirabile.”

HUNTINGTON : AIDS IN TEACHING ANATOMY. 13

Turning now to the development of the lung in the higher verte-

brates, we find that in them the organ first appears as a pouch pro-

truded from the foregut and connected with its lumen by a short and

wide canal, just as in the fish the swim-bladder in its original condition

continues caudad the series of branchial pouch protrusions from the

foregut. (Fig. 9.)

Fig. 8.

Scheme of circulation of Ceratodus.

1, 2, 3, 4. Aortic arches. 1', 2', 3', 4'. Gill capillaries of corresponding arches. 4". Pulmonaryartery. 5. Capillary net-work of swim-bladder or lung. 6. Pulmonary vein. 7. Cardinal veins.

8. Aorta. 9. Ventricle. 10. Auricle. 11. Truncus arteriosus.

Hence, both the air-bladder of the fish and the lung of the higher

vertebrates is ontogenetically a pouch protruded from the foregut. In

its further development the pouch divides, and the canal uniting it to the

oesophagus (ductus pneumaticus) lengthens. The divided pouch forms

the bilateral lung;the duct becomes converted into the trachea and


Fig. 9.

1. (Esophagus. 2. Trachea. 3, 3'. Lungs. 4, 4'. Bronchi.

Fig. 10.

Schematic sagittal section of head and neck, showing connection of laryngeal and pharyngeal

canals.


laryngeal apparatus. The connection of the latter throughout life with

the cavity of the pharynx preserves the original opening leading from

the foregut into the canal of the pneumatic duct. (Figs. 10 and 11.)

The main conclusions which can be based on the foregoing consid-

erations are the following :

1.

Both the air-bladder of the fish and the lung of higher vertebrates

are, ontogenetically, protrusions of the wall of the foregut. The

bladder, usually derived from the dorsal wall, is purely hydrostatic in

function. The lung, always connected ventrally with the foregut, is

respiratory in function.

Fig. 1].

Schematic profile of embryo lung.

1. (Esophagus. 2. Trachea. 3. Lung.

2.

Both the bladder of the fish and the lung of the higher vertebrate

embryo continue caudad the series of the visceral pouches. Hence,

phylogenetically, probably both bladder and lung represent a last

caudal pair of visceral pouches which have not perforated to form

visceral clefts.

The morphological homology of the two structures may be further

accentuated by the following considerations :

1. The internal gill-pouches of the cyclostomes. Form demon-

strated : Bdellostoma stouti (Fig. 12), where the branchial sacs appear as

dilatations of a tubular canal connecting the oesophagus with the exterior.

2. The arrangement of the swim-bladder of Polypterus (Fig. 18),

presenting :

a. A ventral oesophageal opening.

b. A laryngeal-like aditus surrounded by a sphincter.

c. A pneumatic canal, representing the trachea.

d. A bilobed bladder, the right accompanied by the vagus nerve.

3. The structures in Lepidosteus, presenting:

a. A laryngeal apparatus, connected with the beginning of the

pneumatic duct.

b. A vascular trabecular net-work on the internal surface of the

bladder, foreshadowing the batrachian and reptilian lung.

2


4. The structures in the Dipnoi,where the swim-bladder develops

directly as a lung, the pulmonary aditus presenting the same arrange-

ment as in other forms the entrance from the oesophagus into the

pneumatic duct.

Fig. 12.

Foregut, branchial pouches, and canals of Bdellosloma stouti.

The arrows are passed through two of the narrow external openings into the oesophagus,

traversing the branchial canals and the internal gill-pouches.

Form demonstrated : Ceratodus.

The architecture of the lung is next considered in reference to the

bronchial tree and pulmonary vascular supply. The following series is

employed in demonstrating the evolutions of the compound mammalianlung from the simple air-sac.

1. Neeturus. Type of perennibranchiate amphibian lung, consisting

of simple thin-walled air-sac.


Fig. 13.

2. Rana. Batracliian lung. Simple sac, with air-cells.

3. Python molurus, Agkistrodon piscivorus, Ophidian lung, consist-

ing of lung-sac directly continuous with trachea;air-cells and trabeculae

in cephalic portion, gradually becoming less and less

marked in tliin-walled distal portion. Unequal de-

velopment of right and left lung.

4. Iguana tuberculata. Lacertilian lung; air-sac

with one complete septal partition and air-cells in

cephalic portion, simple in distal portion.

5. Chelydra serpentaria. Chelonian lung, with

complete septal system, dividing lung into bronchial

spaces, dorsal and ventral. Monopodic type of di-

vision of bronchial and pulmonary vascular system.

6. Thalassochelys caretta, Loggerhead turtle. Che-

lonian lung presenting direct transition to type of

avian and mammalian lung;

a single axial stem-

bronchus and pulmonary artery, with monopodic

system of division.

The details of structure of the mammalian bron-

chial tree and pulmonary vascular supply are dem-

onstrated by a series of corrosion preparations, special

stress having been laid upon the probable evolution-

ary stages leading to the asymmetrical arrangement

of the right and left bronchial system common to

man and most mammalia. I have a subsequent

communication on this subject to place before the

Association, and will consequently defer the details

until the presentation of my second paper.

The detailed morphology of the human respiratory

tract is next taken up from the descriptive, topo-

graphical, and medico-surgical stand-point. I mayadd that of the nine lectures which I usually devote

to the lungs, two are utilized for the presentation of

the comparative and developmental facts above out-

lined, the remaining seven dealing with the details of structure in man.

It is quite apparent that, in order to carry out the system, much time

and care must be devoted to the formation of a morphological museumfor purposes of illustration. My time and space do not permit me to

enter into a consideration of this important subject, the keynote to the

solution of the entire problem. But I hope on some future occasion

to bring before this Association our plans relating to the formation of

a museum of human and comparative anatomy.

I may in conclusion add, in order that I may not give a somewhat

erroneous impression, that the department of anatomy at Columbia

Swim-bladder of

Polypterus.

1. Larynx-like open-

ing into swim-bladder.


offers laboratory work in comparative anatomy to medical students in

the form of special practical courses in which every student makes his

own dissections on fresh material and records his observations in notes

and drawings. The number of applicants for these courses, which are

optional, and the earnest and intelligent character of the work done give

ample evidence of the educational value of comparative anatomy in

the medical school.

The Medical News.Edited by J. RIDDLE GOFFE, M. D.

PUBLISHED WEEKLY, AT $4.00 PER ANNUM.

THE practitioner who would give his patients the benefit of the latest and best knowledge,and thus most certainly ensure his own success, cannot afford to neglect the medicalweeklies. Foremost among them, as well as cheapest, stands The Medical News. Its

32 quarto pages of reading matter provide space each week to lay before its readers the latest

advances in medicine, surgery, obstetrics, and the various specialties This vast range of infor-

mation is gathered from the whole civilized world by the perfect organization of The News.Its reputation brings to it the contributions of r< cognized leaders of medical thought and practice.

It is a marvel of modern times that the immense body of the world’s advancing knowledge in

medicine can be laid each week upon the table of the subscriber at the comparatively trivial price

of $4 per annum. The secret of course lies in a circulation embracing the most progressive menin the United States and Canada as well as in many foreign countries.

The American Journalof the Medical Sciences.

Edited by ALFRED STENGEL, M. D.

PUBLISHED MONTHLY, AT $4.00 PER ANNUM.

BEING the medium chosen by the best minds of the profession during seventy-nine years for

the presentation of their elaborate papers, The American Journal has well earned the

praise accorded it by an unquestioned authority—“from this file alone, were all other

publications of the press for the last fifty years destroyed, it would be possible to reproduce the

great majoiity of the real contributions of the world to medical science during that period.”

Original Articles, Reviews and Progress, the three main departments into which the contents of

The Journal are divided, will be found to possess still greater interest than in the past. Thebrightest talent on both sides of the Atlantic is enlisted in its behalf, and no effort will be spared

to make The Journal more than ever worthy of its position as the most useful and valuable of

medical magazines.

Progressive Medicine.A Quarterly Digest of New Methods, Discoveries and Improvements in

the Medical and Surgical Sciences.

Edited by HOBART AMORY HARE, M. D.

$10.00 PER ANNUM.**

|PROGRESSIVE MEDICINE” will be modelled upon an entirely novel plan and will

present in an original, narrative form a clear statement of the practical advance made in

every department of medicine and surgery during the year, each specialty being dealt

with by a single authority whose reputation gives ample assurance of accuracy and completeness.

The personal impress of the contributor will be upon each subject;his thoroughly digested narrative

will present its data in due and instructive connection, enchaining the interest, economizing time, yet

giving ample and detailed consideration to all matters which will prove of real value in actual

practice.

Four volumes will be issued each year, the first appearing on March 1st, 1899, and the others

following at intervals of three months. Each will contain from four to five hundred octavo pages,

abundantly illustrated and handsomely bound in cloth.

Expecting appreciation of the self-evident utility of such a work to all practitioners, the pub-lishers confidently anticipate a circulation so general as to justify the very moderate subscription

price of ten dollars for the four volumes. All expenses of delivery will be prepaid.

THE FOLLOWING FAVORABLE COMBINATION RATES ARE AVAILABLE.Alone In Combination

c American Journal ol the Medical Sciences $ 4.00 1 __ )

§ Medical News 4.00/5,7,50 > $15.00

c Progressive Medicine 10.00 j® Medical News Visiting List 1.25"*• Medical News Formulary 1.50, netuCl In all $20.75 for $16.00

‘‘Progressive Medicine,” with the ‘‘American Journal” or ‘‘Medical News,” will be supplied at$13.00, or the ‘‘American Journal,” ‘‘Medical News,” ‘‘ Visiting List” and “Formulary” at $8.50.

$«5-75 $16.00

LEA BROTHERS & CO., Publishers.{ A,

7

J°mTZkSt ' Philadelpl,ia-

Documents

Vertebrates Aids Human Anatomy...adultlowervertebrates,whileheisstudying,microscopically,bysection orreconstruction,the same conditions as temporaryembryonal stages in the development